Theoretical deliberations into metallic Sb/GaAs core/shell nanowire as an optical sensor for NO₂

The rapid industrialization has had devastating effects on the environment, with industries releasing untreated toxic gases into the atmosphere. To address this issue, the development and installation of effective gas sensors for toxic gases are crucial. Recently, various nano- and micro-gas sensors made from lower-dimensional materials (1D and 2D) have been explored. Among these, core/shell nanowires (NWs) have attracted significant interest due to their controllable properties such as electronic bandgaps and optical responses. This study focuses on Sb/GaAs core/shell NWs for optical gas sensing of toxic gases. The Sb/GaAs core/shell NWs exhibit a metallic band structure, attributed to the Sb-5p states near the Fermi energy level in the electronic band structure. Additionally, the gas sensing capabilities of the Sb/GaAs core/shell NWs were investigated. Adsorption energies of approximately − 0.21 eV, -0.25 eV, and − 0.74 eV were observed for CO, NH₃, and NO₂ gases, respectively, indicating physi-adsorption. Optical responses of pristine and gas-adsorbed Sb/GaAs core/shell NWs were also studied, revealing a static reflectance of around 13.57% for NO₂ gas-adsorbed NWs compared to approximately 8.35% for other cases. This suggests that Sb/GaAs core/shell NWs can serve as efficient NO₂ optical gas sensors.